1. Field of the Invention
The present invention relates to a process for purification of a mixture comprising 2,2,3,3-tetrafluorooxetane (hereinafter referred to as "tetrafluorooxetane"). Particularly, the present invention relates to a process for purification of tetrafluorooxetane containing hydrogen fluoride and/or trifluoropropionylfluoride, especially in a small amount.
2. Description of the Related Art
Tetrafluorooxetane is useful as a solvent or a raw material in the production of linear ethers, and can be commercially produced through a reaction of tetrafluoroethylene and paraformaldehyde in anhydrous hydrogen fluoride.
The product produced through the above reaction should be purified since it contains not only tetrafluorooxetane but also, as impurities, hydrogen fluoride and trifluoropropionylfluoride.
In order to purify such a product to obtain tetrafluorooxetane without impurities, a distillation process may be generally employed. However, in view of the fact that hydrogen fluoride has a boiling point of 20.degree. C., trifluoropropionylfluoride has a boiling point of 27.degree. C., and tetrafluorooxetane has boiling point of 28.degree. C., it is very difficult to remove hydrogen fluoride and trifluoropropionylfluoride from tetrafluorooxetane with a distillation process. In particular, when amounts of hydrogen fluoride and/or trifluoropropionylfluoride are very small, for example when the amount thereof is from 500 to 1000 ppm, it becomes even more difficult to remove these impurities from tetrafluorooxetane.
In order to overcome the problem described above, it has been proposed to remove hydrogen fluoride in the reaction product by neutralizing it with aqueous ammonia. However, with the proposed process, additional problems arise in operations of separation and drying after neutralization. Therefore, it is difficult to adopt the proposed process on a commercial scale.